Thermoelectric safety control and switch



Dec. 1, 1942. R. K. ENGHQLDT 2,303,687

THERMOELECTRIC SAFETY COTROL AND SWITCH Dec. 1, 1942- R. K. ENGHoLD-r 2,303,687

THERMOELECTRIC SAFETY CONTROL AND SWITCH Patented Dec. l, 1942 2,303,687 THERMOELECTRIC SAFETY CONTROL AND SWITCH Richard K. Engholdt,

to Milwaukee Gas Specialty Company,

Milwaukee, Wis., assignor Milwaukee, Wis., a corporation of Wisconsin Application March 23, 1939, Serial No. 263,589

17 Claims.

This invention relates to a thermoelectric safety control and switch and, more particularly, is directed to an improved thermoelectric safety control and switch for use with heating and other apparatus, although it isnot limited to such use but may be employed elsewhere as desired.

The particular device which I shall describe hereinafter in connection with the drawings is a thermoelectric safety control and switch for opening and closing a. control circuit for heating apparatus, for example the circuit for a solenoid or motor valvevwhich is held in open or operating position to permit a supply of operative energy to the apparatus as long as the control circuit for the valve is closed and which moves to closed position to shut off the supply of operative energy to the apparatus on current interruption.

The invention, however, is not limited to use in the particular manner above set forth, nor in particular manner shown in the accompanying drawings which are for purposes of illustration only and are not to be construed as a denition of the scope of the'invention, reference being had to the appended claims for that purpose.

For example, the thermoelectric safety control and switch of the present invention may be used in conjunction with valves that require current for both opening and closing, and the thermoelectric safety control and switch may be used for operating alarm circuits and for all similar purposes.

One of the main objects of the present invention is to provide, in a thermoelectric safety control and switch of the character' described, a switch, means for operating the switch, and an electromagnet having an armature, which, when attracted, places the switch under the control of the operating means and, when retracted, prevents operation of the switch by the operating means-in other words, the switch is operable only when the electromagnet is energized and the armature is in attracted position, and is inoperative when the electromagnet is deenergized and the armature is in retracted position.

In its more specific aspects, the switch operating means is operative to set the armature to attracted position, and the movement of the armafture to retracted position on deenergization of the electromagnet operates the switch to safety position, for example to position for movement of the valve to closed position shutting off the supply of operative energy to the apparatus, or to position for operating an alarm circuit or any other desired circuit.

- thermoelectric safety Another object of the invention is to provide, in a device of the character described, a snap acting toggle switch which is adapted to be operated by the switch operating means only when the armature is in attracted position and is prevented from being operated by the switch operating means when the electromagnet is deenergized and the armature is in retracted position.

It is also an object of the present invention to provide a combined thermoelectric safety control device and switch of relatively simple and inexpensive construction and which may be installed and operated conveniently and effectively; also a device of this character composed of relatively few parts and adapted for convenient and expeditious manufacture and assembly, and which operates quickly, positively, and effectively.

Further objects and advantages of the invention will be apparent from the following detailed description, taken in connection with the accompanying drawings in which:

Figure 1 is a fragmentary and more or-less diagrammatic view showing an embodiment of the present invention in a pilot burner and main burner fuel supply system;

Figure 2 is a side view of the thermoelectric safety device and switch;

Figure 3 is a vertical section through the device and switch, taken on the line 3--3 of Figure 2;

Figure 4 is a detail view, partially broken away and showing the snap acting toggle switch of the thermoelectric safety device and switch; and

Figure 5 is a detail perspective view showing the insulated contacts which cooperate with the roller contact of the switch.

Referring now to the drawings which, as above set forth, are for the purpose of illustrating one embodiment of the invention and one particular manner of using the invention and are not to be construed as a definition of the scope of the invention, either as to the form of the embodiment illustrated or as to the illustrated use of the invention, the burner l0 is any `suitable or preferred burner, such as the main burner of a hot water heater, gas furnace, oil heater, automatic space heater, domestic gas range, or `it'may be a conversion burner, or any other burner. l

Associated with the main burner l0 is the usual or any suitable or preferred pilot burner. indicated more or less diagrammatically at l2, which pilot burner is intended to remain lighted for the purpose of relighting the main burner upon extinguishment thereof. .The pilot burner I2 is supplied with gaseous or any other suitable fuel by a tube I3 connected, for example, to the fuel supply conduit I4 which supplies fuel to the main burner.

The conduit I4 is provided with a solenoid er motor valve i5, which valve has a control circuit I6 connected, for example, through a transformer I1, to a suitable source of current, for example to an alternating current circuit I8. For purposes oi' illustration only, it may, be assumed that the valve I5 is of a character to be maintained in open position for a supply of fuel or operative energy to the burner I as long as the circuit I6 is closed, and to operate to closed position to shut oil the supply of operative energy to the apparatus upon interruption of the current by opening the circuit I8.

Of course, by the simple expedient of making additional circuit connections with the switch of the thermoelectric safety control and switch, it may be used in conjunction with valves that require current for both opening and closing. Also, the circuit I6 may be an alarm circuit, or my other desired circuit may be controlled by the switch within the scope of the broader ispects of the present invention.

The thermoelectric safety control and switch, lesignated in its entirety at 20, compr es a ead connection cap and magnet and armature iousing assembly of the general character dis- :losed and claimed in the copending application if Clarence Wantz, Serial No. 239,790, filed Norember 10, '1938.

The lead connection cap 22, which is 'pref- :rably formed of Bakelite" or any other suit ble or preferred insulating material, may be of he form shown, or 'of any other suitable or referred form. It has at its lower end, as 'iewed in Figure 3, an integral cylindrical exension 23 which lits into an opening 24 in one rm of an angular supporting bracket 25. The ap 22 is fastened in place on the bracket 26, or example by cap screws 26.

'Ihe magnet housing 30 is in the form of an .pwardly opening cup-shaped metal shell mounted on the cap 22, for example by secure iressed ilt engagement of its open upper end in he cap 22 at 32. educed at its lower end at 33, and the armaure housing 34, which is also in the form of n upwardly opening cup-shaped metal shell, a mounted on the shell 30for example by a ecure pressed iit engagement of its open upper nd telescopically over the reduced lower end 33 i the shell 30. 'I'he lower end of the shell lis preferably reduced, as shown. The electrolagnet comprises a generally U-shaped magnet 'ame 36 positioned within the shell 30 with itss egs extending through openings in the lower ad of this shell and presenting pole ends within 1e armature housing 34. The magnet frame i has a threaded stud 31 integral therewith, or elded, or otherwise rigidly joined thereto. This .ud 31 extends into an opening or recess 38 in 1e top of the cap 22, and has threaded engage- .ent with a nut member 39 for clamping the iagnet frame rigidly and, at the same time, re- .ovably in place. The nut 39 has a kerf 48 r engagement by a screw driver or other suitile tool, and a spring washer may be provided :tween the nut member 39 and the bottom the recess 38 as indicated at 4I.

Fixed rigidly in thecap 22, as for example by 75 The housing or shell 38 is 50 molding 'the insulating material of the cap thereto and extending endwise from the cap, are a pair of spaced metallic terminal connectors 42 and 43 having aligned openings 44 and split outwardly of these openings as shown at 45. The

electromagnetic coil 46 surrounds the legs of the magnet frame 36, and the leads or ends of this coil extend out through the terminal connectors `42 and 43 and have their bared ends connected to the terminals 42 and 43 at 41 and 48, respectively, in a'manner to have good conducting contact therewith. The connections at 41 and 48 are shown disposed outside of the `cap 22 and laterally of the openings for receiving the terminal means on the thermocouple lead conductors.

'Ihe coil 46 is preferably covered with insulation between its bared ends at 43. Suitable insulation may be. interposed between the turns of the coil 46 and the legs of the magnet frame 36, and between the lower end tracted position against the pole ends o f the magnet frame 36 upon energization of lthe electromagnet. The armature 55 is of disc-like form and is secured to the' upper end of a reciproca- Atory stem or plunger 51. The attachment of the armature to the stem or plunger 61 at 58 is preferably suiliciently loose, as indicated at 59, to permit self-accommodation of the armature to the pole ends of the magnet frame by a gen- 5 erally universal movement of Ithe armature upon the upper end of the stem 51. 'I'he stem 51 is disposed generally concentrically of the armature housing 34 and extends downwardly for reciprocating movement through an opening 60 in the'lower end of the housing 34.

The thermocouple and lead connection therefor are of the general character disclosed and claimed in Oscar J. Leins Patent No. 2,126,564, granted August 9, 1938, and in the copending application of Clarence Wantz hereinbefore identined.

'Ihe thermocouple 65 comprises an outer tubular metallic thermocouple member 66 and an inner metallic thermocouple member 61 disposed within the outer thermocouple member and joined at one end to the outer thermocouple member to form the thermaljunction 68, which is placed in position to be heated by the pilot light I2. An inner lead conductor 69 is joined 5 to theinner thermocouple member to form an internal thermal junction 10, and an outer tubular lead conductor 1I is connected. to the outer thermocouple member through a sleeve 'II' to form a third thermal junction 12. The outer lead conductor 1I encloses the inner lead 6\\ conductor -and; with the outer thermocouple `\member. constitutes an enclosure about the inner thermocouple member and the inner lead conductor and the inner thermocouple junction 10. 'I'he inner lead conductor 69 is insulated from the outer lead conductorby a wrapping of insulation on the inner lead conductor as indicated at 14, or by an oxide coating, or otherwise as desired.

The inner and outer lead conductors 69 and Il are preferably of a character that will permit bending, as desired, to permit disposing the thermocouple in any desired position. At the same time, the lead connection is preferably of a charactcr to support the thermocouple in-any desired opening 44 in one the bracket 25, which arm |00 4over the bifurcated outer The inner end of the member I I8 has an insulat-` position, although supporting brackets or other means may be employed for supporting the thermocouple and lead connection. At the opposite A end, the inner lead conductor 33 extends from the outer lead conductor 1I and has a metallic terminal sleeve 15 fixed thereon in good conductive contact therewith and spaced from the end of the lead conductor 1|. is interposed between the terminal sleeve 13 and the adjacent end of the outer lead conductor 1I.

A quick detachable connection is thus provided between the thermocouple leads and the terminals 42 and 43 for the electromagnet coil 40. The thermocouple is connected to the terminals 42 and 43 by slipping the terminal end of the thermocouple lead means through the opening 44 in one terminal 43 and into the opening 44 in the other terminal, with the terminal sleeve 13 in the terminal 42 and the end of the tubular thermocouple lead 1| in the opening 44 in the other terminal 43. The screws are then tightened to clamp the split portions 45 of the terminals 42 and 43 into good conductive contact and gripping engagement with the terminal sleeve 15 and tubular lead 1 I respectively. The thermocouple is disconnected from the device by loosening the screws 80 and withdrawing the terminal end of the thermocouple leads from the terminals 42 and 43.

The snap acting toggle switch, designated in its entirety at |00, is of existing form except for the manner in which it is combined with the thermoelectric safety control of the present invention, and, for certain the desired combination for the purposes of the present invention.

The switch |00 comprises a pair of aligned contacts |0| and |02 and a third contact |03 insulated from each other and bound together with a plurality of insulating strips |04. The contacts |0|, |02 and |03 and the insulating strips |04 are secured together into a unitary assembly by securing means indicated at |05.

This contact and insulating strip assembly is secured at in a metal cradle |01 which is pivoted to turn freely on the inner end of a sleeve |08 which extends inwardly from the arm |03 of is disposed'at right angles to the arm of the bracket to which the thermoelectric safety control is secured. A shaft ||0 is journaled for rotation in the sleeve |03 coaxial with the axis of switch cradle |01. A knob or finger piece |I2 is fixed on the outer end of the shaft III), for example by a screw |I4. The shaft IIO is adapted to be rotated by grasping the finger piece I I2 and turning the same.

Fixed upon the inner turn therewith is a switch actuating arm |I5. The outer end of the arm I I5 is turned back, and the end has a rounded point at I I6. This pointed end ||6 engages in the bifurcated outer end of a contact roller actuating member I I8 and in a depression I|3 in an element |20 which is slipped end of the member IIB.

ing tip |20' which is notched to engage the reduced intermediate portion |2| of the roller contact |22. A coiled spring |23, surrounding the member IIB and interposed between the element |20 and an abutment |24 on the member IIB, snaps the roller contact |22 from the position shown, in which it engages the contacts |02 and |03, to the opposite end of the arcuate track |25, at which position it engages the contacts |0| and features, to the end of eiiiectingV end or the shaft un te An insulating sleeve 11 |03. The intermediate insulated portion of the track I is preferably raised to engage in the reduced intermediate portion of the contact roller |22 to guide the same in its movement.

One end of the roller contact |22 makes contact at all times with the contact |03, which is of full length, with a contact edge presented throughout the full length of the arcuate track |20 for continued contact with the roller |22. The contacts |0| and |02 are insulated from each other at |28. It will thus be apparent that when the roller |22 is in the position shown, it bridges the contacts |02 and |03, and when snapped to the opposite position by the toggle action upon turning the nnger piece II2, it bridges the contacts |0| and |03. Each contact |0|, |02 and |03 has a terminal |30 for connection, for example, to a three-wire control circuit. In the illustrated embodiment of the invention, the control circuitis a two-wire circuit, one Vwire or con- Y Y ductor I8 being connected to the terminal of the contact |02 and the other wire or conductor I8' swinging movement of the being connected to the 'contact |03. It will thus be apparent that when the roller contact |22 is snapped'by the toggle action into engagement with the contacts |02 and |03, the circuit I0 is closedthereby energizing the valve I5 to maintain same in open position for supplying operative energy to the apparatus. When the roller contact |22 is snapped to its opposite position, it ceases to bridge the contacts |02 and |03, and the circuit I6 is interrupted, thereby releasing the valve I5 for movement, for example, by a spring (not shown) to closed position, shutting oir the supply oi operative energy to the appa.- ratus.

The outer end of the stem or plunger 51 of the thermoelectric control device is bifurcated and fits over and is pinned at |40 to a connecting member |42, which connecting member is, in turn, pivoted by one of the pins or a screw |06 to the switch cradle |01. A helical spring |44 is interposed between a plate |45 at the bottom of the armature housing 34 and the shoulder means |46 on the connecting link |42.

The operation of the device is as follows:

When the pilot light I2' is burning, the heat thereof upon the thermal `iunction 68 produces a thermoelectric current in the coil 46. The magnet frame 3B and armature 55 are preferably formed of an alloy of relatively low magnetic reluctance, and, as a result, the relatively weak thermoelectric current produces a magnetic field of suilicient strength so that when the armature is placed in contact with the pole ends of the magnet frame as shown in Figure 3, the magnetic attraction holds the armature in attracted position against the magnet frame with a force greater than the force exerted by the spring |44, thereby holding the switch cradle |01 and contact assembly |0|, |02 and |03 in the position as shown in Figure 3.

If the pilot iiame is extinguished, the holding action of the electromagnet ceases to be sumcient to hold the armature 55 in attracted position, and the spring |44 swings the switch cradle |01, and the contacts |0|, |02 and |03 carried thereby, clockwise as viewed in Figure 3, generally to the position shown in dotted lines. Movement of the cradle |01 from the full line position to its dotted line position as the armature moves to retracted position moves the contact |02 out of engagement with the roller contact |22, thereby opening the control circuit I0 and releasing the shutoff valve I5 for movement to closed position.

When it is desired to reset the device, the nnger piece ||2 is grasped and turned in a direction to swing the lower end of the actuating member I I8, as viewed in Figure 4, counterclockwise, the member I| being positioned opposite the position in which it is shown in Figure 4 before the finger piece is turned. understood that the member IIB has assumed this position opposite to that shown in Figure 4, relative to the carrier or cradle |01 and its contacts, for example by swinging of the carrier |01 to the dotted line position shown in Figure `3 upon release of the armature by deenergization of the electromagnet. Alternatively, the member I I8 and the roller contact |22 actuated thereby may be positioned opposite the position shown in Figure 4 by turning the nger piece in a. direction to actuate the roller contact |22 to such positionv out of engagement with the contacts |02, |03 when the armature is held in attracted position.

Assuming that the member ||8 is positioned opposite the position shown in Figure 4, rotation of the finger piece ||2 in a counterclockwise direction as the parts are viewed in Figure 4 causes the member ||8 to engage the insulating strip assembly at |60 and, through this assembly, to swing the cradle |01 therewith. This swingingv Iets. to be movement of the cradle'in a counterclockwise direction, as viewed in Figure 3, actuates the stem 51 inwardly and sets the armature 55 into attracted position. As, positioned at the beginning of this resetting movement, the shaft I|0 is stopped against turning movement in the opposite direction, or against retrograde turning movement, by engagement of a pin |62 thereon with a stop |63 (Figure 2). 1

If the pilot burner l2' is lighted and sets up a thermoelectric current to hold the armature in attracted position as it is reset to this position by. turning the finger piece |I2 the cradle |01 is held against swinging movement in the opposite direction with the switch actuating arm H5. At the same time, in resetting the armature to attracted position the pin |62 moves away from the stop |63. Therefore, the shaft IIO and the arm IIS carried thereby may now be turned in the opposite direction, and thecradle I 01, being held against movement with the shaft IIJ by the magnetic attraction which holds the armature attracted, turning of the knob II2 in the opposite direction snaps the contact |22 into engagement with -the contacts |02 and |03, thereby/closing the circuit I6 to actuate valve I5 to open position.

If, on the other hand,A the pilot burner is not ignited. to produce the thermoeiectric current for holding the armature in attracted position, the switch cradle |01 will follow the movement of the shaft I|0 and switch actuating member IIO, so that turning of the shaft in the opposite direction after resetting the armature to attracted position will turn the contact assembly IGI, |02 and |03 freely therewith so as not to close the circuit I6. In other words, unless the electromagnetl is energized and the armature held in attracted position, there will be no movement of the contact roller |22 relative to the cooperating contacts, thus making it impossible to close the circuitv I6 when the electromagnet is deenergized.

It will be understood that where the fuel supply tube I3 for the pilot burner is connected to the fuel supply duct I4, the connection will .preferably by-pass the valve I5 orbe disposed the anterior to the valve I5 so that there will be a supply oi' fuel to the pilot burner when the valve I5 is closed.

I do not intend to be limited to the precise details shown or described.

I claim:

1. In a device of the character described, in combination, a control device having an electromagnet provided with an armature and adapted when energized to hold said armature in at.- tractedposition and when deenergized to release said armature for movement to retracted position, switch means controlled by said electromagnet and comprising switch contact means mounted for swinging movement and connected to said armature, toggle actuated and snap acting contact means CQQperable with said first contact means, means for operating said last con- .2. In a device of the character described, in"

combination, a control device having an electromagnet provided with an armature and adapted when energized to hold said armature in attracted position and when deenergized to release said armature for movement to retracted position, contact means connected to said armature, cooperating contact means adapted for actuationv in one direction to actuate said first contact means in one direction and thereby set said armature in attracted position through the connection between-the armature and said first contact means, said cooperating contact means being adapted for actuation in the opposite direction relative to said rst contact means when the electromagnet is energized and the armature is held in attracted position and actuating said iirst contact means therewith in the opposite direction when the electromagnet is deenergized, said cooperating contact means comprising a toggle actuated snap acting roller contact and said rst contact means comprising contacts `in sulated from each other and adapted for contact with said roller contact, and means for operating said roller contact.

3. In a device of the class described, in combination, a control device having an electromagnet provided with an armature and adapted when energized to hold said armature in attracted position and when deenergized to release said armature for movement to retracted position, a support, contact means pivoted on said support and connected to said armature, a shaft mounted for rotation the pivot for said irst contact means, a linger piece forA turning said shaft, contact means cooperatingv with said first contact means and adapted to be actuated in opposite directions by said shaft upon turning movement thereof, and stop means for preventing retrograde actuation of said cooperating contact means from substantially the positionA normally occupied by said contact means whenv the electromagnet is deenergized.

4. In a device of the class described. in comcoaxially with respect toY bination, a control device having an electromagnet provided with an amature and adapted when energized to hold said armature in attracted position and when deenergized to release said armature for movement to retracted position, a support, contact means pivoted on said support and connected to said armature, ashaft mounted for rotation coaxially with respect to the pivot for said first contact means, a finger piece for turning said shaft, contact means cooperating with said first contact means and adapted to' be actuated in opposite directions by said shaft upon turning movement thereof, and spring means interposed between a relatively fixed abutment and' said first contact means for actuating said rst contact means to a safety position and said armature to retracted position when the electromagnet isdeenergized.

5. In combination, first contact means mounted for swinging movement in opposite directions, holding means comprising an electromagnet which, when energized, is adapted for holding said contact means against swinging movement in one direction, operating means rotatable in one direction to move said first contact means to the position in which said first contact means is held by said electromagnet when energized, and second contact means actuated relative to said rst contact means by rotation of said operating means in the opposite direction only when said first contact means is held by 'said electromagnet.

6. In combination. first contact means mounted for swinging movement in opposite directions, holding means comprising an electromagnet which, when energized, is adapted for holding said contact means against swinging movement in one direction, operating means rotatable in one direction to move said first contact means to the position in which said rst contact means is held by said electromagnet when energized, second contact means actuated relative to said first contact means by rotation of said operating means in the` opposite direction only when said first contact means is held by said electromagnet, and means for limiting rotation of said operating means to one direction from the position from which it is operated to move said rst contact means to the position in which said first contact means is held by said electromagnet and permitting rotation of said operating meansin the opposite direction from said last mentioned position.

7. In combination, iirst contact means mounted for swinging movement in opposite directions, holding means comprising an electromagnet which, when energized, is adapted for holding said contact means against swinging movement in one direction, operating means rotatable in one direction to move said first contact means to the position in which said first contact means is held by said electromagnet when energized, second contact means actuated relative to said rst contact means by rotation of said operating means in the opposite direction only when said rst contact means is held by said electromagnet, and a toggle connection between said operating means and said secondv contact means for providing a snap action of said second contact means.

E. In combination, a pivoted contact carrier, rst contact means carried thereby, an electromagnet, an armature for said electromagnet which, when attracted. is adapted to hold said contact carrier against turning movement in one direction, operating means rotatable in one direction to move said armature to attracted position and to swing said contact carrier to the position in which it is held when said armature is attracted, and second contact means operatively connected to said operating means to be actuated by. said operating means into contact with said rst contact means to complete an electric circuit by rotation of said operating means relative to said contact carrier in the direction in which movement of said contact carrier is restrained by atiraction of said armature by said electromagne 9. In combination, a pivoted contact carrier, rst contact means carried thereby, an electromagnet,. an armature for said electromagnet which, when attracted, is adapted to hold said contact carrier against turning movement in one direction, operating means rotatable in one direction to move said armature to attracted position and to swing said contact carrier to the position in which it is held when said armature is attracted, second contact means adapted to be actuated into contact with said first contact means to complete an electric circuit by rotation of' said operating means relative to said contact carrier in the direction in which movementof said contact carrier is restrained by attraction of said armature by said electromagnet, and a toggle connection between said operating means and said second contact means for providing a snap action of said second contact means.

10. In combination, a pivoted contact carrier, first contact means carried thereby, an electromagnet, an armature for said electromagnet which, when attracted is adapted to hold said contact carrier against turning movement in one direction, operating means rotatable in one direction to move said armature to attracted position and to swing said contact carrier to the position in which it is held when said armature is attracted, second contact means operatively connected to said operating means to be actuated by said operating means into contact with said first contact means to complete an electric circuit by rotation of said operating means relative to said contact carrier in the direction in which movement of said contact carrier is restrainedbyattraction of said armature by said electromagnet, and means for moving said armature to retracted position upon deenergization of said electromagnet with an accompanying swinging movement of said contact carrier in a direction to disengage said first contact means from said second contact means to open the electric circuit.

l1. In combination, a pivoted contact carrier, a a pair of contacts carried by said carrier for pivotal movement therewith, holding means comprising an electromagnet which, when energized, is adapted for holding said carrier and the contacts carried thereby against swinging movement in one direction, operating means rotatable in one direction to move said carrier and the contacts carried thereby to the position in which said carrier and contacts are held by said electromagnet when energized, a roller contact, and a toggle connection between said operating means and said roller' contact for actuating saidk roller contact into'position bridging said first contacts by rotation of said operating means in the opposite direction only when said carrier and said first contact means are held by said electromagnet.

12. In combination, a pivoted contact carrier, a pair 'of contacts carried by said carrier for pivotal movement therewith, holding means comprising an electromagnet which, when energized,

.is adapted for holding said carrier and the contacts carried thereby against swinging movement iin one direction, operating means rotatable in one direction to move said carrier and the contoggle connection between said operating means and said, roller contact for actuating said roller contact into position bridging said nrst contacts by rotation oi' said operating means in the opposite direction only when said carrier and said rst contacts are held by said electromagnet, and means for actuating said carrier and said first contacts in a direction to move said first contacts out of contact with said roller contact upon deenergization of said electromagnet.

13. In combination, a pivoted contact carrier, a pairV oi.' contacts carried by said carrier for pivotal movement therewith, holding means comprising an electromagnet which.. when energized, is adapted for holding said carrier and the contacts carried thereby against swinging movement in one direction, operating means rotatable in one direction to move said carrier and the contacts carried thereby to the position in which' said carrier and contacts are held by said'electromagnet when energized, a roller contact, a toggle connection between said operating means and said roller contact for actuating said roller contact into position bridging said nrst contacts by rotation of said operating means in the opposite direction only when said carrier and said ilrst contacts are held by said electromagnet', means for actuating said carrier and said first contacts in a direction to move said first contacts out of contact with said roller contact upon deenergization of said-electromagnet, and means for limiting rotation of said operating means to one direction from the position from which it is operated to move said carrier and the contacts carried thereby to the position in which said carrier and contacts are held by said electromagnet and permitting rotation of said operating means in the opposite direction from said last-mentioned position.

14. In combination, a pivoted contact carrier, ilrst contact means carried by said carrier, spring means for turning said carrier in one direction, an electomagnet. an armature for said electomagnet and having pivotal connection with said carrier to hold' same when attracted against actuation by said spring means, operating means rotatable in one direction to' move said armature to attracted position against th'e action oi' said spring means and said carrier to the position in which it is held when said armature is attracted, and second contact means adapted to be actuated into contact with said iirst contact means to complete an electric circuit by rotation of said operatingl means relative to said contact carrier in the directicn in said contact carrier is restrained by attraction of said armature by said electromagnet and only when said contact carrier is held by said electromagnet, said spring means actuating said carrier in a direction to open the circuit, when said eleczromagnet is deenergized to release said armaure.

15. In combination, a pivoted contact carrier, iirst contact means carried by said ca'rrier, spring means for turning said carrier in one direction, an electromagnet; an e., mature oi' said electro magnet and having pivotal connection with said carrier to hold same, when attracted, against actuation by said spring means, operating' means rotatable in one direction to move said armature to attracted position against the action of said spring means and said` carrier to the position in which' it is held when said armature is attracted. second contact means adapted to be actuated into contact with said first contact means to complete an electric circuit by rotation of said operating means relative to said contact carrier in the direction in which movement of said contactV carrier is restrained by attraction of said armature by said electromagnet, said spring means actuating said carrier in a direction to open the circuit when said electromagnet is deenergized to release said armature, and a toggle connection between said operating means and said second contact means` for providing a snap action oi said second contact means.

16. In combination, an electromagnet, an armature for said electromagnet, first contact means connected to said armature, second contact means for engagement with said rst contact means, and means operable to reset said armature to attracted position and operatively connected to said second contact means to actuate said second contact means into engagement with said first contact means only when said armature is held in attracted position'by said electromagnet.

17. In combination, an electromagnet, anarmature for said electromagnet, first contactv means connected to said armature, second contact means for engagement with said first contact means, and means operable to' reset said are mature to attracted position and operatively connected to said second contact means to actuate said second contact means into engagement with said nrst contact means only when said armature is held inattracted position by said electromagnet, resetting movement being imparted to said armature by movement of said operating means in one direction and said second contact means being actuated into engagement with said first contact means by said operating means upon movement thereof in a dinerent direction.

RICHARD K. ENGHOLDT. 

